Appendix C Ad590 And Lm335 Sensor Calibration; Ad590 Sensor - ILX Lightwave Temperature Controller LDT-5525 User Manual

AD590
AND
The LDT-5525 Temperature Controller uses two constants (C1 and C2) for
calibrating linear thermal sensing devices, such as the AD590, and the LM335.
C1 is used as the linear or zero offset value, and C2 is used as the slope or gain
adjustment. Therefore, C1 should be set to a nominal value of 0, and C2 should
be set to a nominal value of 1, when the SENSOR SELECT switch is in the
AD590, or LM335 positions.
In order to calibrate a linear sensor device, the sensor must be operated at an
accurately known, stable temperature. For example, the sensor may be calibrated
o
at 0 C if the sensor is placed in ice water until its temperature is stable. A highly
accurate temperature probe, thermometer, environmental chamber, etc., may also
be used to determine the known temperature for calibration. This appendix
contains one and two point calibration methods for linear sensor devices. These
methods will work for either type of device.

AD590 Sensor

The AD590 is a linear thermal sensor which acts as a constant current source. It
produces a current, i, which is directly proportional to absolute temperature, over
its useful range (-50
i = 1µA / K
- where i is the nominal current produced by the AD590, and K is in Kelvin.
The LDT-5525 Temperature Controller uses i to determine the nominal
temperature, T , by the formula:
n
T = ( i / ( 1µA / K ) ) - 273.15
n
o
- where T is in
n
The temperature, T
is first calibrated as follows:
LM335 S
o o
C to +150 C). This nominal value can be expressed as:
C.
, which is displayed by the LDT-5525 Temperature Controller
d
A P P E N D I X
C
ENSOR ALIBRATION
C
37
LDT-5525